Project Summary/Abstract Among men who have sex with men (MSM) in the US, annual rates of new HIV infections continue to grow, despite stability or decline among other at-risk groups. This trend is due in part to unprotected sexual behavior that poses high per-act transmission risk. Alcohol increases the risk for HIV infection among MSM, likely due to alcohol's association with increased unprotected sexual behavior. Past studies suggest that alcohol intoxication specifically co-occurs with increased odds of engaging in sexual behavior that poses high transmission risk. However, the mechanisms by which alcohol intoxication leads to increases in sex risk among MSM are poorly understood, and experimental research on alcohol's on sexual decision-making among MSM has been limited to date. An improved knowledge of these mechanisms may uncover critical opportunities to enhance existing interventions designed to reduce alcohol-related sex risk, and could point to new pathways for intervention development. Alcohol has been shown to impair executive functions (EF) that are key to regulating behavior, such as inhibitory control and executive attention, and these impairments may underlie alcohol-related increases in sex risk. Alcohol has also been shown to increase the influence of automatic processes, such as automatic affective reactions and attention biases to sexual stimuli, on behavior. As such, alcohol's tendency to increase sex risk may be due to the tendency for automatic processes to increasingly guide behavior when intoxicated, the impairment of EFs that typically moderate the influence of these processes and other impulses, or both. The proposed 3-year study will examine the effects of alcohol intoxication on sexual decision-making and behavior among MSM using a video-based sexual scenario task. This research will also examine potential mechanisms of alcohol's effects on sex outcomes, using path modeling to test indirect effects between alcohol intoxication and sex risk via EFs and automatic processes. To accomplish these goals, we will employ a between-subjects experimental design with 3 conditions (true control, placebo, and alcohol [0.08%]). The long-term goal of this research is to advance theoretical understanding of the alcohol-risky sex link, and to use this knowledge to guide a future line of research focused on developing and testing new approaches to intervention for MSM. This goal is vital given recent findings from intervention research with other behaviors suggesting that many of the processes examined in the proposed study are modifiable, and that changes in these processes produce corresponding changes in behavior. As such, this research has high potential to make critical contributions to the effort to find ways to reduce the spread of HIV among MSM.